Journal of contaminant hydrology最新文献

{"title":"Characteristics of polycyclic aromatic hydrocarbons along an urban river in snowmelt and non-snowmelt periods from Northeast China","authors":"TeRi GeLe ,&nbsp;Kaijun Lu ,&nbsp;Zucheng Wang ,&nbsp;Shasha Liu ,&nbsp;Ziping Liu","doi":"10.1016/j.jconhyd.2025.104828","DOIUrl":"10.1016/j.jconhyd.2025.104828","url":null,"abstract":"<div><div>The polycyclic aromatic hydrocarbons (PAH) concentrations along an urban river from Northeast China were investigated during snowmelt and non-snowmelt periods. The results showed that the concentration of dissolved PAHs in the samples collected during the snowmelt period ranged from 61 to 271 ng L⁻¹, significantly lower than those in the non-snowmelt period, which ranged from 141 to 833 ng L⁻¹ (<em>p</em> &lt; 0.05). The highest PAH concentrations in river were generally observed at municipal sewage treatment outlet. PAH concentrations were positively correlated with SUVA₂₅₄ value (<em>p</em> &lt; 0.01) and negatively correlated with dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) (<em>p</em> &lt; 0.01). PAH concentration increased from the upstream suburbs to urban areas, and downstream suburbs in snowmelt period, whereas an opposite trend was observed during non-snowmelt periods. These findings indicate that different factors control PAH concentration distribution along the urban river during two periods. However, despite the spatial distribution pattern of PAHs along the upstream-downstream gradient changing due to snowmelt, the overall PAH levels during snowmelt were not higher than those observed in the non-snowmelt period. This study implies that snowmelt may not always rapidly increase PAH concentrations in aquatic environment, especially in urban rivers.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104828"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145850447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the spatiotemporal dynamics and source characteristics of nutrients under anthropogenic pressure in Taipu River, China","authors":"Tong Wang ,&nbsp;Jiayi Kou ,&nbsp;Fengjunxi Chen ,&nbsp;Yalong Li ,&nbsp;Yaojen Tu ,&nbsp;Yanping Duan","doi":"10.1016/j.jconhyd.2025.104835","DOIUrl":"10.1016/j.jconhyd.2025.104835","url":null,"abstract":"<div><div>Surface water quality dynamics is a pivotal factor in sustainable water management. As a strategic waterway in Taihu Lake Basin (China), Taipu River plays a key role in integrating water management through flood control, water supply, and ecological preservation across Jiangsu, Zhejiang, and Shanghai. However, under evolving anthropogenic pressures, systematic studies characterizing its nutrient spatiotemporal variations and pollution drivers remain limited. In this study, the spatiotemporal (October 2020–July 2021 from upstream to downstream) distributions and source characteristics of key nutrients from Taipu River were evaluated through various water quality index methods, coupled with multi-approach source apportionment (principal component analysis and positive matrix factorization). Results indicated that the concentrations of total nitrogen (TN) and chemical oxygen demand (COD) in Taipu River gradually increased from upstream (TN: 0.9–1.2 mg L⁻¹, COD: 11.5–15.2 mg L⁻¹) to downstream (TN: 1.1–1.9 mg L⁻¹, COD:11.0–21.7 mg L⁻¹), and exceeded regulatory Class III limits in summer/winter (&gt;1.0 mg L⁻¹) and spring/autumn (&gt;20 mg L⁻¹), respectively. The increased TN likely resulted from nitrogen fertilizer loss due to rainfall, whereas the increase in COD is probably linked to the release of metabolic products from algae. Water contamination analyses identified a slightly-contaminated T7 site (i.e., TN = 1.51 ± 0.71 mg L⁻¹, COD = 34 ± 9.0 mg L⁻¹, exceeding Class IV), with primary contamination sources attributed to industrial activity (e.g., textile industry). For this T7 site with slight water contamination, the in-situ remediation strategies such as adding synthetic microbiomes, incorporating aquatic plants, and engineering intervention for nitrogen and COD pollution are recommended. These findings highlight the urgent requirement for targeted measures to mitigate nitrogen/COD loads, which is crucial to improve water quality and ecosystem health of the Taihu Lake Basin.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104835"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transport, retention and degradation of the urban biocides terbutryn, diuron and octylisothiazolinone and the herbicide acetochlor in urban surface-soil interfaces","authors":"Tobias Junginger ,&nbsp;Sylvain Payraudeau ,&nbsp;Felicia Linke ,&nbsp;Jens Lange ,&nbsp;Gwenaël Imfeld","doi":"10.1016/j.jconhyd.2025.104788","DOIUrl":"10.1016/j.jconhyd.2025.104788","url":null,"abstract":"<div><div>Urban biocides, including terbutryn, diuron, and octylisothiazolinone (OIT), commonly leached from facade coatings during rainfall-runoff events, can infiltrate subsurface environments through permeable urban surfaces, posing a risk to groundwater quality. Despite frequent detection of biocides in urban groundwater, the transport and transformation processes occurring at the surface-soil interface remain insufficiently characterized. This study combines outdoor lysimeter experiments with reactive transport modeling and compound-specific isotope analysis (CSIA) to assess biocide leaching, retention, and degradation across three typical urban interfaces: gravel strips, permeable pavements, and vegetated soils. Leaching of biocides differed among lysimeters, with 10–17 % of terbutryn, 40–47 % of acetochlor, and 5–40 % of diuron released from the gravel and pavement systems, whereas leaching from vegetated soil was minimal (&lt;0.5 %). OIT was not detected in any leachates, likely due to rapid degradation. Eight-year modeling further indicated limited retention in gravel and pavement, with up to 36 % and 22 % of the applied terbutryn mass, respectively, migrating to depths greater than 30 cm. In contrast, vegetated soils retained over 99 % of terbutryn mass, primarily through sorption and biodegradation. CSIA indicated higher biodegradation rates in pavements than in gravel. Measurements and modeling showed substantial transformation of terbutryn into transformation products. These results underscore the critical role of biogeochemical processes at surface–soil interfaces in regulating biocide transport to groundwater. Permeable, non-vegetated surfaces receiving facade runoff were identified as significant contributors to subsurface contamination. The study highlights the limited and variable retention capacity of different urban surfaces and stresses the need to integrate biocide control into sustainable stormwater management practices.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104788"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring different modification methods of biochar for Se(IV) removal from water: Synergistic effect of adsorption and reduction","authors":"Yu-Ying Wang ,&nbsp;Juan Yu ,&nbsp;Rong-Ting Jiao ,&nbsp;Li-Li He ,&nbsp;Yao Su ,&nbsp;Yun-Long Wang ,&nbsp;Hui Lin ,&nbsp;Yan Shi ,&nbsp;Hao-Hao Lyu","doi":"10.1016/j.jconhyd.2026.104863","DOIUrl":"10.1016/j.jconhyd.2026.104863","url":null,"abstract":"<div><div>Selenium (Se) is a vital micronutrient for humans health; however, elevated concentrations can result in numerous health problems and negatively impact ecosystems. This study examines the influence of two distinct modification approaches (pre- and post-treatment) on the physicochemical properties of biochar and its efficacy in removing selenite (Se(IV)) from water. A comprehensive characterization of unmodified biochar (BC), pre-treated biochar (Fe/Mn-impregnated biochar, F-Fe/Mn-BC), and post-treated biochar (Fe/Mn-oxide-loaded biochar, A-Fe/Mn-BC) was carried out using a suite of advanced analytical techniques. To determine the optimal parameters, a systematic key parameters affecting adsorption performance was conducted by varying the initial pH, contact time, initial Se(IV) concentration, and the presence of coexisting ions. The findings indicate that A-Fe/Mn-BC has a higher adsorption capacity for Se(IV). A-Fe/Mn-BC achieved a maximum adsorption capacity of 248.8 mg∙g⁻¹, which is roughly threefold higher than that of both BC and F-Fe/Mn-BC. The removal mechanism involves surface adsorption accompanied by the reduction of Se(IV) to elemental selenium (Se(0)), with Fe(II) and Mn(II) species on the biochar surface acting as electron donors. Furthermore, the presence of common coexisting ions in solution had negligible effects on Se(IV) removal efficiency. These findings indicate that post-treatment modification enhances biochar performance more effectively than pre-treatment, and suggest that A-Fe/Mn-BC nanomaterial demonstrated remarkable potential for use in the treatment of Se(IV) contamination.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104863"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the protection of aquifers against pollution risks in karstic areas (PAPRIKA) method for predicting Cryptosporidium contamination","authors":"Damien Costa ,&nbsp;Maria A. Stoica ,&nbsp;Gladys Foissey ,&nbsp;Venceslas Villier ,&nbsp;Romain Coppée ,&nbsp;Antoine Morel ,&nbsp;Romy Razakandrainibe ,&nbsp;Loïc Favennec ,&nbsp;Philippe Audra ,&nbsp;Matthieu Fournier","doi":"10.1016/j.jconhyd.2026.104860","DOIUrl":"10.1016/j.jconhyd.2026.104860","url":null,"abstract":"<div><div><em>Cryptosporidium</em> spp. are protozoan parasites worldwide distributed, frequently responsible for gastrointestinal outbreaks from waterborne and foodborne origins. Overall European increase cryptosporidiosis incidence have recently been reported. Aim was to evaluate a specific intrinsic vulnerability mapping method for karst aquifers (PaPRIKa method) for application to <em>Cryptosporidium</em> contamination. Risk zones were mapped using the PaPRIKa vulnerability method enabling identification of sampling sites. From January to July 2021, eight sampling sites were investigated monthly. <em>Cryptosporidium</em> and bacterial contamination were evaluated using standard methods and confronted to water conductivity, turbidity, temperature and precipitation data to investigate potential correlation. Until 87% of sampling sites preselected using the PaPRIKa method were contaminated by <em>Cryptosporidium</em> suggesting the relevance of the method for identifying the most vulnerable sites. Oocysts were infectious in 81% of cases.Water temperature and precipitations influenced <em>Cryptosporidium</em> contamination. In the context of global changes where it is expected increase of waterborne disease, efficient tools to predict <em>Cryptosporidium</em> water resources contamination are mandatory. We suggest use of predictive tool for identification of vulnerable sites to monitor integrating nature of soils, levels of precipitations, soil saturation, land cover, urban waste and rearing areas.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104860"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of key control factors on pollutant migration by suspended cutoff walls in contaminated sites","authors":"Honghan Dong ,&nbsp;Yun-Min Chen ,&nbsp;Wenjie Xu","doi":"10.1016/j.jconhyd.2026.104867","DOIUrl":"10.1016/j.jconhyd.2026.104867","url":null,"abstract":"<div><div>This study develops a two-dimensional numerical model for seepage and pollutant transport in sites with suspended cutoff walls, grounded in the advection–dispersion equation. The impacts of key factors, including the pressure head of the pollution source, the site's horizontal hydraulic gradient, and the horizontal distance between the downstream wall and the pollution source, on the non-linear seepage distribution and the wall's anti-pollution performance were investigated. Centrifuge model tests were conducted to confirm the numerical model's dependability. Furthermore, the concentration at the downstream wall bottom reaching 10% <em>C</em>₀ was established as the threshold for identifying the suspended containment system's failure. The research findings demonstrate that modifications to the site flow field due to parameter changes are a significant factor contributing to the macroscopic variations in pollutant migration. As the pressure head of the pollution source diminishes from 1.2 m to 0.3 m, the peak flow velocity at the mid-point of the liner bottom reduces by 25.6%, while the service life of the wall extends by 51.1%. The site flow-field distribution is significantly impacted, with the wall's service life increasing by 209.1% and 22.8%, respectively, as the site's horizontal hydraulic gradient decreases from 0.04 to 0.01 and the horizontal distance between the downstream wall and the pollution source increases from 4 m to 16 m. Therefore, the design of suspended cutoff walls in risk control of contaminated sites with deeply buried aquitards should focus on aspects related to these three factors.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104867"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Explainable advanced modelling of interfacial tension in H2 – CO2 – CH4 – brine systems for sustainable subsurface storage in saline aquifer","authors":"Saad Alatefi ,&nbsp;Okorie Ekwe Agwu ,&nbsp;Menad Nait Amar ,&nbsp;Ahmad Alkouh","doi":"10.1016/j.jconhyd.2025.104827","DOIUrl":"10.1016/j.jconhyd.2025.104827","url":null,"abstract":"<div><div>Hydrogen is increasingly recognized as a pillar of future low-carbon energy systems, offering flexibility across multiple sectors and contributing to deep decarbonization goals. To enable large-scale deployment, Underground Hydrogen Storage (UHS) in geological formations such as saline aquifers is gaining considerable attention as a strategic option for ensuring secure and scalable energy reserves. The safety, efficiency, and operational success of UHS heavily depend on accurately determining interfacial tension (IFT) between hydrogen/cushion gas and the in-situ brine, as this parameter governs several critical phenomena related to storage performance. This study aims to develop a reliable and explainable machine learning framework to predict IFT in H₂/cushion gas–brine systems across diverse thermodynamic and compositional conditions. Two input schemes were explored: the first included nine variables covering detailed salt composition, pressure, temperature, and the presence of cushion gas (represented by average critical temperature, T_cm); the second used a simplified set of four inputs, namely equivalent salinity, pressure, temperature, and T_cm. A curated database of approximately 500 experimentally measured IFT data points was employed to train and validate three models: radial basis function neural network (RBFNN), generalized regression neural network (GRNN), and categorical boosting (CatBoost). Among these, the CatBoost-based model under the simplified scheme achieved the highest predictive accuracy (R² = 0.9979, RMSE = 0.5136 mN/m), with excellent physical consistency and generalization. Trend analysis confirmed the model's ability to replicate expected IFT behavior under varying conditions. Comparative benchmarking showed that the CatBoost model outperformed several state-of-the-art models from the literature. A leverage-based applicability domain analysis revealed that 97 % of the data points fall within acceptable influence and residual bounds, confirming robustness. Beyond accuracy, the model is highly interpretable globally and locally using SHAP and LIME techniques, making it suitable for real-time deployment in UHS operations to support safe injection design and long-term storage reliability.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104827"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145863168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal variability in the hydrogeochemical behavior and metal fluxes of acid mine drainage: Implications for long-term output and treatment","authors":"David M. Singer,&nbsp;Rachel Izworski,&nbsp;Annika Dudik,&nbsp;Allyson C. Tessin","doi":"10.1016/j.jconhyd.2025.104818","DOIUrl":"10.1016/j.jconhyd.2025.104818","url":null,"abstract":"<div><div>The timeframe for when water quality impairment from acid mine drainage (AMD) from abandoned coal mines might end is often poorly constrained. The response of AMD composition to changes in discharge can provide insight into how mines store and release water and solutes. This work aimed to determine seasonal variability, hydrogeochemical behavior, and metal fluxes from two abandoned coal mines in Appalachian Ohio that represent end-member hydrologic conditions within the Huff Run (HR, groundwater-fed) and Yellow Creek (YC, surface water-fed) watersheds, by: (1) monitoring AMD output to establish seasonal variability; (2) comparing current output to publicly available historical data; and (3) linking metal loadings in the AMD from each mine to characteristics of the coal and abandoned mine works. The HR AMD was dominated by chemostasis (“pipe-full”), whereas the YC AMD was dominated by dilution (“not pipe-full”). For HR, the combination of continuously flooded mineworks recharged primarily by groundwater combined with the presence of fine-grained, diffusely disseminated pyrite in the host rock results in slower AMD production, although shorter timeframe for water quality impairment (decades) given current conditions. In contrast, the faster pace of YC AMD depletion is likely due to the combination of pseudokarstic flow conditions fed by surface water with large, seasonal pulses of dissolved metals from the weathering of coarse-grained aggregates of pyrite but a longer timeframe for AMD impairment to cease (decades to centuries). These results highlight the importance of establishing how the combination of local and regional conditions influence the timeframe for on-going AMD production.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104818"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the carbon cycle of surface water-groundwater in the Jianghan Dongting Plain of the Yangtze River Basin, China","authors":"Meiyan Hu ,&nbsp;Peijiang Zhou ,&nbsp;Chao Meng ,&nbsp;Xiaobin Li ,&nbsp;Xiaoxi Chen ,&nbsp;Jingyi Xie ,&nbsp;Shengkai Cao ,&nbsp;Xiaodi Zhang ,&nbsp;Zhen Ni ,&nbsp;Guangshui Na","doi":"10.1016/j.jconhyd.2025.104812","DOIUrl":"10.1016/j.jconhyd.2025.104812","url":null,"abstract":"<div><div>Carbon cycle research is the core foundation for understanding the root causes of climate change and developing effective emission reduction strategies. Carbon source-sink dynamics in the water ecologic environment is the key component of the carbon cycle in basins. Jianghan Dongting Plain of the Yangtze River Basin is rich in water resources, but lacks a comprehensive understanding on the carbon source-sink dynamics of water environment. The study integrated literature data and self-tested data to research the carbon source-sink dynamics in surface water and groundwater in the Jianghan Dongting Plain. The study found that there was a coupling effect of HCO₃⁻ and DOC between SW (surface water) and GW (groundwater) in the Jianghan-Dongting Plain of the central Yangtze River Basin. The HCO₃⁻ in surface water may come from the recharge of groundwater, and the DOC in the groundwater may come from the recharge of surface water. In addition, the high concentration of NH₄⁺-N in groundwater inhibited the release of DOC from the sediment into the groundwater. Decreasing of situation index (SI) values of calcite and dolomite from west to east indicated that under the coupling effect between surface water and groundwater, the water carbonate interaction was enhanced, leading to the carbon sink changing to be carbon source from west to east. The study clarified the spatial pattern of regional carbon effects of “ west sink and east source” for the first time, elevating carbon cycle research from a single water body to a system level of “surface water groundwater continuum”, successfully connecting micro biogeochemical processes with macro regional carbon cycle patterns, which is of great significance for carbon cycling research in the Yangtze River Basin and predicting future environmental changes.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104812"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Density-dependent flow, solute transport and mixing in the Fraser River delta aquifer","authors":"Yaguang Zhu ,&nbsp;Kun Jia ,&nbsp;Roger D. Beckie","doi":"10.1016/j.jconhyd.2025.104816","DOIUrl":"10.1016/j.jconhyd.2025.104816","url":null,"abstract":"<div><div>Groundwater flow in coastal aquifers is influenced by density differences between freshwater and saline water, forming a complex density-dependent flow system. The relatively narrow zone where freshwater and saline water mix is the location of strong geochemical gradients, which can drive reactions. Understanding the dynamics of this mixing zone is crucial to understand the biogeochemical reactions that occur during saline intrusion. In this study, we characterized flow and dispersive mixing in a confined sand aquifer subjected to saline intrusion, using both field observations and numerical modeling. Observations from an extensive monitoring network revealed a saline wedge extending approximately 500 m inland. We simulated density-dependent flow with MIN3P and used PEST++ to estimate dispersivity and diffusion from field observations. In effect, we use salinity data to measure the dispersivity through inverse modeling. The longitudinal and transverse dispersivity were calibrated at 0.1 m and 0.001 m, respectively, while the molecular diffusion coefficient was 1.2 × 10⁻⁹ m²/s. Sensitivity analyses show that transverse dispersivity affects mixing-zone characteristics more than longitudinal dispersivity. Our results highlight the importance of accurately estimating dispersivity values to model the width of the mixing zone, which strongly controls geochemical reactions at the site. These findings provide insights into the processes driving freshwater–saline water mixing in coastal aquifers and offer guidance for future modeling studies on geochemical dynamics during saline intrusion.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"277 ","pages":"Article 104816"},"PeriodicalIF":4.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}